+7+5+3+1-1-3-5-7Levels BeforePilot Addition(Pilot=1.25)832 Symbols4Symbols511Symbols63Sym-bols63Sym-bols24Sym-bols63Sym-bols104SymbolsPN511PN63PN63PN63VSBModeReserved12Sym-bols* For trellis coded terrestrial 8 VSB the last 12 symbols of the previous segmentare duplicated in the last 12 reserved symbols of the field sync.SyncPrecode*Field Sync is Repeated Every 24 ms

55

8-VSB-

Field Sync

7

1

2

3

4

5

6

0

Before Equaliser

After Equaliser

8-VSB Frame

832

Symbolsper DataSegmentof 77.3 µs

Data

Data

Training Sequence

Training Sequence

Sync

The Training Sequence is only 0.3% of signal time

Total Sync is only 0.8% of time

313 Data

Segments

of 24.2 ms

57

DVB-T-

Carriers + Pilots

Kmin

SYMBOLS IN SEQUENCE-

68 PER BLOCK.

Kmax

1704 for 2K or

6816 for 8K

Kmax =

Modulated Carriers

0.977/3.906 kHz

Scattered Pilots

58

DVB-T Super Frame

Super

Frame

4 x 68

Symbols

=

N MPEG

Packets

45/177

TPS Carriers

Fixed Pilots

Frame 1

Frame 2

Frame 3

Frame 4

54

48

34

50

17/68

1512:

1705

in 2k

6048:

6817

in 8k

Co-

Incident with Scattered pilots

59

DVB-T Transmission Frame

Data

Scattered Pilot

TPS-

Pilot

Continuous Pilot

Kmin=0

Kmax

Carrier Spacing & Position

2k mode-

3906 Hz-

Kmax=1704

8k mode-

977 Hz-

Kmax=6816

Symbol Duration 256 us (2k) or 1024 us (8k)

60

DVB-T-

Estimating the Channel

A

B

C

D

E

A

B=3/4A+1/4E

C=1/2(A+E)

E

D=1/4A+3/4E

A to E

-

1.024 ms (2k)

-

4.096 ms (8k)

For a varying transmission channel

DVB-T estimation is 23.5 times faster than ATSC

61

DVB-T-

Estimating the Channel

A B C D E F G

A to D-

11.724 kHz (2k)

-

2.931 kHz (8k)

For a varying transmission channel

DVB-T estimation is 23.5 times faster than ATSC

A B C D E F G

B=2/3A+1/3D

C=1/3A+2/3D

E=2/3D+1/3G

F=1/3D+2/3G

62

Channel Estimation &Equalisation

Time

Time

ATSC

DVB-T

63

Estimation Rate Comparison

ATSC Equaliser is updated every 24 ms

(~260 000 symbols)

DVB-T Equaliser is updated every symbol period(256 us).1/12

of data carriers are pilots

DVB-T Full Channel estimate is available every4 symbols (1.024 ms)

For a varying transmission channel DVB-Testimation is at least 23.5 times faster than ATSC